trying to compile Tcl 8.5.12 for Windows using mingw32-w64, I got some errors during "make install".
The reason is the fact that "make install" assumes that the newly built tclsh can be executed. That, of course, does not work when cross-compiling.
I'd like to offer you a patch for this issue.
The changes made to configure.in and Makefile.in enable us to use the build machine's tcl to run the helper scripts.
When cross compiling, make will use the tclsh provided to configure via RUN_TCLSH or a tclsh which is in the PATH.
If there's no tclsh found, a warning gets printed but install succeeds. Hope it's useful.